Lately he’d been thinking about what should come next. What, he’d been asking, is the next great computation platform? What comes after the smartphone? Zuckerberg believed that the answer was headsets that provide “immersive 3-D experiences”—movies and television, naturally, but also games, lectures, and business meetings. These headsets would eventually scan our brains, then transmit our thoughts to our friends the way we share baby pictures on Facebook today. “Eventually I think we’re going to have technology where we can communicate our full sensory experience and emotions to someone through thought,” he told me in an interview in his office. Then he added, helpfully, “There’s a lot of interesting research into that, where people have some band on their head…. You can look into it if you’re interested.”

It sounded a little bit insane, but Zuckerberg wasn’t joking. “There are certain things in the future that you know will happen,” he continued. “The real challenge is figuring out what’s possible now and how exactly do you make it.”